The Mars rover Opportunity is wheeling off on what could be its final mission, and is starting a two-year journey that it may not even complete. The small robot climbed out of the Victoria crater a few weeks ago, and NASA‘s science team has now decided to direct Opportunity towards an even larger crater, known as Endeavor.

The 7-mile stretch between Victoria and Endeavor craters matches the total distance the rover already has covered in the 4 1/2 years since landing on the planet. “We may not get there but it is scientifically the right direction to go anyway,” said [researcher] Steve Squyres…. “This crater (Endeavor) is staggeringly large compared to anything we’ve seen before” [Reuters].

Endeavor measures almost 14 miles in diameter, and its deep crater would allow Opportunity to study old layers of rock to learn about Mars‘ geological history. But even if the rover never makes it to the crater, researchers say the journey will pay scientific dividends; along the way are small rocks strewn about the surface that appear to have been dug up by meteor impacts farther away, giving scientists the chance to examine material that otherwise would be too deep to reach [Reuters].

Opportunity and NASA’s other rover, Spirit, have continued to operate long past their original life expectancy of three months, but both aging rovers have encountered some mechanical difficulties; Spirit has a jammed front wheel that requires it to drive backwards, and Opportunity has a faulty shoulder joint that prevents it from stowing its robotic arm.

But the explorers have also received some help recently that should speed Opportunity on its journey: The rovers downloaded new software in 2006 that gives them more autonomy in choosing routes and avoiding hazards, and they’ll also be assisted by satellite images of the ground taken by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter, which arrived in Mars orbit in 2006. This tool can capture details smaller than the rover itself. “HiRISE allows us to identify drive paths and potential hazards on the scale of the rover along the route,” [NASA official John] Callas said [SPACE.com].